Brake mechanism



M. TIBBETTS June 24, 1930.

BRAKE MECHANISM Filed March 21. 1928 l v1 ne n hw .iai-re ai, ieeenutren STATES PATENT ermee MILTON TIBETTS, OF DETROIT, MICHIGAN,ASSIGNOR T PACKRD MOTOR CAR COMPANY, 0F BETROIT, MICHIGAN, A CORPORATION0F MICHIGAN BRAKE MECHANISM Application led March 21,

This invention relates to motor vehicles and more particularly to theclutch and brake mechanism.

Before the advent of self-energizing, servo 6 and power brakes for motorvehicles, the force required to brake the vehicle by the operation ofthe usual foot lever provided for the purpose was great enough to imposesomething of a burden upon the operator of 10 the vehicle due to thefact that the braking force depended entirely upon the pressure appliedto the brake lever by the operator. This burden, however, has beenlightened to various extents by the adaptation of self energizing, servoand power brakes to motor vehicles since with these types of brakes,thel pressure on the foot lever necessary for braking is generally lessthan the pressure required when such brakes are not employed.

his is true to the greatest extent with power rakes, such as airpressureor vacuum operated brakes where the foot lever merely serves to operatea valve controlling the brakes, the pressure on the foot lever re- 25quired to apply the brakes with this system being relatlvely ver Ismail.

But whereas the orce necessary to be apl plied to the brake lever may bereduced to very low limits by the use of power brakes, er thev like, theextent to which the force may be reduced that is required to release theclutch of the vehicle by operating the clutchlever is decidedly limited.The factorsA determining this limit are the clutch pressure spring andthe length of the effec'- tive or operative path of travel of the clutchlever vor pedal. The clutch pressure spring must be of sufiicientstrength to prevent slip-. ping of the clutch when engaged and theoverall length of travel of the clutch 'lever must be short enough sothat the clutch may be conveniently operated with the foot of theoperator.` The effective. or operative length of travel is somewhatshorter than the overall length of travel of the clutch lever because ofthe clearance necessary between the beginning of the clutch releasingmovement and the ullyretracted'position of the clutch. Thus the pressurethat must 1928. Serial No. 263,304.

be overcome in releasing the clutch cannot be reduced beyond a certainamount and the levera e availabletovovercome this pressure is limlted bythe shortness of the path 'of travel of the clutch lever..

It is apparent therefore that the force required to release theclutchbyoperating the clutch lever is more or lessxed or cannot bereduced beyond a certain amount while the force necessary to apply thebrakes by the operation of the brake lever may be reduced to very lowlimits b the use of power brakes. But with power brakes, it isundesirable to have too small a resistance to the operation of the brakelever, because of the 35 Vtendency toward over-braking or locking of thewheels. In some instances, this tendency toward over-braking has beenlessened by loading the'brake operating lever in some convenient mannerso as to provide a greater resistance to the o eration oi the brakelever in applying the rakes. However, instead of loading the brake levermerely for the purpose of providing resistance to its operation, thisinvention provides that a 5 part .of the resistance to the operation ofthe clutch lever in releasing the clutch be transerred tothe brake leverand thus provide suficient resistance to the operation of the brakelever to lessen the tendency toward over-braking while atthe same time,the operation of, the brake lever will assist in releasing the `clutchwith the result that the force required to operate the clutch will morenearly approximate the force required to apply the brakes.

It is accordingly an object of the present invention to provide meansthat will assist in releasing the clutch and thus diminish 9 the forcerequired to disengage the clutch when the. brakes are applied. v

Another. object of the invention is to provide means that willautomatically assist in releasing the clutch when the brakes of thevehicle are applied.

Another object of the invention is to -so interconnect the clutch andbrakes of a motor vehicle that application of the brakes 10o will tendto operate but will not be sutlcient to release the clutch.

Another object of the invention is to so relate the operating levers ofa clutch and 5 a power operated brake that the resistance to operationof the clutch lever will approximate the resistance to operation of thebrake lever. y Other objects of the invention will appear from thefollowing description taken in connection with the drawing -formingapart of this specification, in which:

The ligure is aplan view of part of a motor vehicle showing the clutchand brake 15.operating levers and other adjacent parts,

embodying the invention.

Referring to the drawing, l0 represents a flywheel and clutch housing ofa motor vehicle having a clutch 11 mounted therein, the clutch being ofany desired type for connecting the motor crank shaft with thetransmission or gear box o the vehicle. The transmission is enclosed ina housin 12 onthe upper portion of which is mountetgl a change speedlever 13 and extending from the rear end of the housing 12 is a driveshaft 14. connected to the transmission through the usual universaljoint 15. The clutch is shown as having a spring 16 adapted to normallyengage the clutch friction parts, and aclutch lever or pedal 17 mountedfor pivotal movement in any convenient manner, is connected with acollar 18 in any desired or suitable manner, such as by means of a shaft19 and a shifter forl 20, for operating the clutch or moving it to itsdisengaged or open position, this movement takin place against theaction of spring 16. r he upper end of lever '17 is located so as to beengaged and operated with the foot ofA the operator of the vehicle.

The brakes of the vehicle are operated by a brake lever or pedal 21mounted for pivotal movement in any suitable manner, the upper end ofwhich is positioned so that it may be readily engaged and operated bythe foot of the operator of the vehicle. The brakes-may be of anydesiredtype suchv as the ordinary mechanical brakes or hydraulic brakes or/they may be self-energizing, servo or power brakes since the invention1s adaptable to either of these types of brakes. However, the inventionis particularly well adapted to power brakes, because with this type theforce required, tokoperate the brake lever or pedal is relatively verysmall due to the fact that the brake lever serves merely to operate avalve controlling the brakes. Thebrake lever or pedal 21 is connected tothe power brake in anyv suitable manner and in the drawing, thisconnection .and the power brake are shown more or less diarammatically,the' power brake mechanism 65 eing shown at 22' and the connectionbetween the brake mechanism and the brake lever being shown at 28.

Disengagement of the clutch is assisted when the brakes are applied andpart of the resistance to the operation or disengagement of the clutchis transferred to the brakes by interconnecting the clutch and brakelevers or pedals. In the form shown, this interconnection is a spring,preferably a .coiled spring 24 having one end 25 secured to the brakelever 21 and the other end 26 engaging the clutch pedal 17 so that asthe brake pedal is operated to apply the brakes, 'the spring will becoiled and will exert a pressure on the clutch lever. The spring 24 maybe placed in any convenient position or location with respect to theclutch vand brake levers, but it is preferably coiled around the shaftupon which the clutch and brake levers are pivoted, or around the clutchand brake lever pivotal extensions as shown.

From the above description, it will be seen that when the brakes of thevehicle are applied by the operation-of the brake pedal 2l, spring 24will be coiled by movement of spring end 25 with the brake lever andcause spring end 26 to exert a pressure on the clutch pedal 17, thustransferring a portion of the resistance to operation of the clutchlever to. disengage the clutch to the brake lever when the brakes areapplied. Ater the vehicle has been slowed down sufiiciently with thebrakes applied, the clutch lever is operated to release the clutch, thisrelease being assisted by the pressure exerted by spring 24 on .theclutch lever. It will be understood that spring 24, even when coiled tothe greatest extent by movement of the brake lever, will never exertsucient pressure on the clutch lever to operate the lever and disengagethe clutch. In other words, the spring merely tends to operate theclutch, but is not sutiicient to release the clutch when the brakes areap lied.

ith a motor vehicle having power brakes and having the clutch and brakelevers interconnected, as described, it will be apparent that the forcerequired to disengage the clutch will more nearly approximate the forcerequired to apply the brakes, the closeness of the approximationdepending, of course, upon the spring interconnecting the clutch andbrake levers. Thus, for example, if it requiresl a force of only 10pounds to operate the brake lever tofapply power brakes, and pounds torelease the clutch, a spring adapted to exert a force of 20 pounds onthe clutch lever when the brakes are applied will remove 20 pounds fromthe resistance to operation of the clutch and add 20 ,pounds to the4force reuired to operate the brakes, making a orce of only 30 poundsrequired to operate the clutch lever and 30 pounds to operate the brakelever. The advantages of such an equalization of the forces required onthe part of the operator of thevehicle to operate the clutch and brakeswill be apparent.

It Will be noted that end 26 of spring 24 is not secured to the clutchlever, but preferably merely bears against th?J lever. This arrangementprevents the eXtra loading of the clutch lever that would be occasionedby uncoiling of the spring When it is necessary to release the clutchbefore the brakes are applied or without applying the brakes.

It will be understood that various forms of the invention other thanthose described above maybe used Without departing from the spirit orscope of the invention.

Having thus described the invention, whatjis claimed and desired to besecured by Letters Patent is:

1. In a motor vehicle, the. combination with a clutch and a brakemechanism, of means tending but not suiiicient to operate the clutchwhen the brake mechanismis applied.

2. In a motor vehicle, the combination with a clutch anda brakemechanism, of means interconnectin the clutch and brake tending but notsu cient to operate the clutch when the brake mechanism is` applied.

3. In a motor vehicle, the combination with a clutch and a brakemechanism, of an interconnection for said clutch' and brake tending butnot suiiicient to operate the cllnth when the brake mechanism is app ie4. In a motor vehicle, the combination with a clutch and its operatinglever and a brake mechanism and its o rating lever, of meansinterconnecting said levers tending but not sufficient to operate theclutch when the brake mechanism is applied.

5. In a motor vehicle, the combination with a clutch anda brakemechanism, of yielding means .connecting the clutch and rake mechanismtending but. not suicient to operate the clutch when the brake mechanismis aplied.

6. In a motor vehicle, in combination, a clutch and a brake mechanism',and a spring connecting the clutch and brake mechanism tending but notsufficient to operate the clutch when the brake mechanism is applied.

7. In a motor vehicle, in combination, a clutch and a brake mechanism,separate o erating means for the clutch and bra e mechanism, and meansunder the control of the brake operating means tending but notsufficient to effect disengagement of the clutch.

8. In a motor vehicle, in combination, a clutch and a brake mechanism,operating means for the clutch and brake mechanism, and yielding meansunder the control of the brake operating means tending but not`suflicient to efect disengagement of the clutch. v

9. In a motor vehiclehaving a brake mechanism and a spring closedclutch, separate operating means or the brake mechanism and clutch andmeans connecting said operating means to only partially counter? ture.

MILTON TIBBETTS.

